feat(lua_adc): add adc demo lua script

components/lua_modules/lua_module_adc/lua_scripts/basic_adc.lua

@@ -0,0 +1,30 @@
+local adc = require("adc")
+local delay = require("delay")
+
+local ADC_GPIO = 4
+local SAMPLE_COUNT = 5
+local SAMPLE_INTERVAL_MS = 200
+
+local ch = adc.new(ADC_GPIO)
+
+print(string.format(
+    "[adc_demo] reading gpio=%d for %d samples...",
+    ch:gpio(),
+    SAMPLE_COUNT
+))
+
+for i = 1, SAMPLE_COUNT do
+    print(string.format(
+        "[adc_demo] sample %d/%d: %d mV",
+        i,
+        SAMPLE_COUNT,
+        ch:read()
+    ))
+
+    if i < SAMPLE_COUNT then
+        delay.delay_ms(SAMPLE_INTERVAL_MS)
+    end
+end
+
+ch:close()
+print("[adc_demo] done")